The hertz (symbol Hz) is a unit of frequency in the International System of Units (SI). It is defined as the number of cycles per second of a periodic phenomenon. The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The infrared spectrum, (including near infrared, mid-infrared and far infrared), are segments of the electromagnetic spectrum with longer wavelengths than those of visible light, extending from a nominal red edge of the visible spectrum at 700 nanometers (nm) to 1 mm. This range of wavelengths corresponds to a frequency range of approximately 430 Terahertz (THz-1012 Hz) down to about 300 GHz (three hundred billion hertz). THz and sub-THz include segments of the electromagnetic spectrum between about far infrared and microwave, which have a wavelength of about 3 mm to about 1 μm, corresponding to frequencies that range from about 100 GHz to 30 THz. These segments of the spectrum cannot be easily gauged with the optical and electronic measurement techniques normally associated with adjacent regions of the spectrum.
It is understood by those skilled in the art that it is possible to use the terahertz segment of the electromagnetic spectrum for diagnosis of dental disease or tissue changes in the hard and soft tissues of an intra and extra oral complexes. For example, use of the electromagnetic spectrum within the terahertz range is well established to diagnose dental decay more accurately and at an earlier stage than other ionizing x-ray techniques. This concept can also be used to illustrate multi-dimensional shapes of such anatomical structures using appropriate hardware and software to convert wave forms into identifiable anatomical images. Typically the waves of this spectrum penetrate the tissue and reflect back to a detector, where they will be read and analyzed. This specific segment of the electromagnetic spectrum will only emit non-ionizing radiation, as compared to other conventional diagnostic tools such as the x-ray or gamma ray that can damage tissue cells.
Advances in technology have made possible the production and detection of infrared radiation with devices that are mobile and operate at room temperature. Perhaps the most commonly used generation method, in medical applications, employs optical rectification, whereby high frequency oscillations of a femtosecond laser pulse are rectified by an optical crystal, leaving only the envelope of the laser signal which is a THz pulse.
What is needed is a device and method that uses an alternative diagnostic means that is mobile, encompasses use of a wide range of the electromagnetic spectrum, has minimal biological adverse effect on the human cells and is practical enough to be used multiple times.